In recent years, a communication technology has existed whereby communication or power transfer between desired points on a two-dimensional signal transmitting apparatus is realized by using electromagnetic coupling of a local electromagnetic field. This is a communication technology that enables communication or power transfer between desired communication couplers via a signal transmitting apparatus in a communication system in which a grid-like pattern is provided in a planar surface of the signal transmitting apparatus, and a communication coupler for communication or power transfer is disposed on the grid-like pattern.
For such a communication technology, a communication system as shown in FIG. 18 to FIG. 20 is provided, for example.
The communication system shown in the figures includes a sheet-like signal transmitting apparatus 1, serving as a communication medium, and a communication coupler 2. The signal transmitting apparatus 1 is a sheet-like structure, and has a ground layer 3, a grid-like pattern electrode 4, a protective layer 5, and a dielectric layer 6. The ground layer 3 forms a lower electrode. The grid-like pattern electrode 4 is a mesh shape, and is located at a distance from the ground layer 3. The protective layer 5 is provided on the top of the grid-like pattern electrode 4, and prevents the pattern electrode 4 from making contact with the communication coupler 2 directly. The dielectric layer 6 is provided in a region sandwiched between the ground layer 3 and the grid-like pattern electrode 4.
As shown in FIG. 20, the communication coupler 2 has a plate shaped antenna circuit 10 for communication signals or power transmission and reception, a signal/power transmission and reception circuit (omitted from the figure), which are disposed on the signal transmitting apparatus 1, and a cup-shaped coupler case 11 which is formed such that it covers the antenna circuit 10.
With such a construction, communication signals are turned into an electromagnetic field via the antenna circuit 10 of the coupler case 11, and after being injected into the signal transmitting apparatus 1, are propagated through the signal transmitting apparatus 1 so that communication is performed between the communication coupler 2 and another communication coupler (omitted from the figure).
Other than the technology shown in the above-described FIG. 18 to FIG. 20, as shown in Patent Documents 1 to 3, a technology is disclosed in which, in a communication apparatus, an electromagnetic field is made to exist in a region sandwiched by sheet-like bodies, being current-carrying parts facing each other, and an electromagnetic field is advanced by changing the applied voltage between the two sheet bodies.
Especially in Patent Document 2 among these Patent Documents, a communication coupler with the construction shown in FIG. 21 is disclosed.
A communication coupler 20 has an inner conductor 21, an outer conductor 23, and a coaxial cable 24 as shown in the cross-sectional diagram of FIG. 21. The inner conductor 21 is disk-shaped. The outer conductor 23 is cup-shaped, covers the inner conductor 21, and forms a coupler case 22. The coaxial cable 24 is connected to the inner conductor 21 and the outer conductor 23. The end of the coaxial cable 24 is connected to the communication equipment 25. With such a construction, an electromagnetic field input and output from the communication equipment 25 is transmitted to the coaxial cable 24, and after it is propagated between the inner conductor 21 and the outer conductor 23 of the communication coupler 2, and injected into the signal transmitting apparatus 1, it is propagated in the signal transmitting apparatus 1, so that communication is performed between the communication coupler 20 and another communication coupler (omitted from the figure).
In Patent Document 4, a technology regarding a communication device is disclosed, which includes a position retention mechanism that performs position adjustment such that electrostatic coupling is effected between electrodes at the tips of surface wave transmission line parts installed in a transmission electrode and a reception electrode, and furthermore retains the position.